Conventional refrigeration and air-conditioning systems include a compressor, a condenser, an expansion device, and an evaporator. Refrigerant is circulated through the system to produce cooling. Energy is provided to the system by the compressor which serves to create a source of high pressure gas refrigerant which is allowed to pass through the condenser. The refrigerant dissipates heat in the condenser and changes state to a high pressure liquid. The refrigerant then passes through the expansion device and into the evaporator where the refrigerant changes from a high pressure liquid to a low pressure liquid, and subsequently to a low pressure gas. The change of state removes heat from the area surrounding the evaporator. The refrigerant is then drawn from the evaporator back to the compressor in a low pressure gas form, where it is again compressed into high pressure gas for repetition of the cycle.
An accumulator is normally located between the evaporator and the compressor in the system. The accumulator ensures that only refrigerant in a gas or vapor stage passes into the compressor, as refrigerant from the outlet of the evaporator typically includes both a liquid component and a vapor component. In some accumulators, the vapor component is collected in the upper region of the accumulator, while the liquid component, along with any lubricating oil, drains to the lower region of the accumulator. The vapor component of the refrigerant is removed from the upper region of the accumulator by a U-shaped or J-shaped return conduit. The return conduit typically includes a metering device (e.g., a bleed-through orifice) at the lower portion thereof which draws a small amount of oil (and liquid refrigerant) back into the return tube for lubrication of the downstream components, for example, the compressor.
One drawback associated with some accumulators has been that under certain operating circumstances (such as during start-up), incoming refrigerant enters the accumulator at high velocities and if directed at the stored liquid refrigerant, can disrupt and splash the stored liquid refrigerant. Such splashing can cause uncontrolled return of the refrigerant through the return conduit to the compressor, which is undesirable in certain circumstances.
Some accumulators include a baffle or deflector which is supported within the inlet stream of refrigerant. The deflector or baffle prevents the incoming refrigerant from impacting directly against the stored liquid refrigerant, and instead causes the incoming refrigerant to enter the stored liquid smoothly. The deflector or baffle also facilitates separating the gaseous refrigerant from the liquid refrigerant.
On particularly useful accumulator with a baffle is illustrated in U.S. Pat. Nos. 4,651,540; 5,076,071; and 4,627,247. These patents show a helical baffle disposed at the upper part of the accumulator housing. The helical baffle receives the incoming refrigerant, and directs the refrigerant in a spiralling downward path along the inside surface of the housing. The liquid refrigerant is separated from the gaseous refrigerant by centrifugal force and flows downwardly to join the liquid stored in the lower portion of the housing. The spiralling refrigerant smoothly enters the stored liquid without substantial splashing, and thus without causing uncontrolled return of the liquid refrigerant to the compressor. It is believed that this type of accumulator is also efficient, relatively low-cost to manufacture, and effectively separates gaseous refrigerant from liquid refrigerant.
Nevertheless, it has been found that with this type of accumulator, oil can separate from the stored liquid because the stored liquid is relatively inactive. The oil floats to the top of the stored liquid where it is unavailable to the submerged oil return orifice of the return tube. This can reduce the amount of oil returned to the compressor for lubrication purposes, which can also be undesirable in certain circumstances.
As such, it is believed there is a demand in the industry for a further improved accumulator which allows controlled, agitated introduction of the liquid refrigerant into the stored liquid to prevent or reverse oil separation from the stored liquid, and which prevents uncontrolled liquid return to the compressor. It is also believed that there is a continuous demand in the industry for an efficient and low-cost accumulator which effectively separates gaseous refrigerant from liquid refrigerant.